Area Prioritization for Insect Pollinator Communities on an Oceanic Island
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Arquipelago - Life and Marine Sciences ISSN: 0873-4704 Area prioritization for insect pollinator communities on an Oceanic Island ANA PICANÇO, F. RIGAL & P.A.V. BORGES Picanço, A., F. Rigal & P.A.V. Borges 2017. Area prioritization for insect pollinator communities on an Oceanic Island. Arquipelago. Life and Marine Sciences 34: 85- 104. Conservation studies usually assess the effectiveness of protected areas and draft proposals on the inclusion of new areas to gain legal protection status, paying little attention to the unprotected surrounding matrix of the respective protected areas network. By combining species distribution modeling and a site selection method, we aim to quantify the contribution of different land uses to insect pollinator conservation on a small oceanic island i.e. Terceira Island (Azores, Portugal). Our results showed that, in addition to well preserved and protected native forest in Terceira, other land uses, such as naturalized vegetation areas, exotic forests, and semi-natural pastures, could serve as a continuum for the protected areas network. This result suggests that protecting marginal non-natural areas may also be important, especially when areas with well- preserved natural habitats are scarce. This spatial planning approach can be easily applied to other islands in the archipelago and any similar island systems, to better plan conservation efforts (such as habitat restoration) and to design specific buffer zones around a protected areas network. Key words: Land-use planning, insect pollinator representation, spatial conservation planning, Zonation, species distribution modeling. Ana Picanço (e-mail: email: [email protected]), François Rigal, P.A.V. Borges, cE3c – Centre for Ecology, Evolution and Environmental Changes/ Azorean Biodiversity Group and University of the Azoress – Faculty of Agricultural and Environmental Sciences, Rua Capitão João d’Ávila, PT-9700-042 Angra do Heroísmo, Azores, Portugal. François Rigal, Environment and Microbiology Team, MELODY group, Université de Pau et des Pays de l’Adour, IPREM UMR CNRS 5254, BP 1155, 64013 Pau Cedex, France. INTRODUCTION affording some insights into reserve network design, the guidelines provided by IBT offer little Spatial conservation planning methods have been explicit guidance for decision-makers who face strongly influenced by the Island Biogeography specific choices about how many and which sites Theory (IBT) of MacArthur & Wilson (1967), or which spatial configuration have to be which has played a pivotal role in the incorporated in a reserve network. establishment of the concept of natural reserves There is currently a broad consensus that (Triantis & Bhagwat 2011). IBT-based managing the landscape matrix also matters, approaches usually make the assumption, which because standard reserve systems will never cover is often invalid, that reserves are isolated habitat more than a small fraction of the globe; and islands embedded in a matrix of unfavorable human-induced habitats dominate most terrestrial terrain (Franklin & Lindenmayer 2009). Despite ecosystems (Vitousek et al. 1997; Pereira & Daily 85 Picanço et al. 2006; Newbold et al. 2013). Therefore, proper changes and massive species introduction driven conservation planning should take into by the development of local agriculture and consideration not only the human-perceived urbanization, the increase in seaborne world trade native habitat patches, but also the extensive areas routes (for which oceanic islands form a strategic that surround them (Franklin & Lindenmayer node) and recently by the growing popularity of 2009). For this reason, reserve selection shifted oceanic islands as world-class tourist destinations its focus to systematic conservation planning (Walker & Bellingham 2011). Hence, there is an framework developed to efficiently identify urgent need to improve the conservation of island conservation areas, with its emphasis on ecosystems to better preserve their unique biota quantitative targets, that guarantee species and the services that they may supply for human representation and persistence, the two most communities (Walker & Bellingham 2011). important conservation planning objectives Several policy conservation action strategies have (Margules & Pressey 2000; Moilanen et al. 2009; already been produced for islands, namely The Fattorini et al. 2012). Representation refers to the CBD Global Island Partnership (GLISPA targets defined to achieve the number of each http://www.cbd.int/island/glispa.shtml; visited species that should be contained within a system Nov 2 2016), the Samoa Pathway (see of conservation areas, and persistence refers to http://www.sids2014.org/samoapathway) and the long-term survival of the species achieved by BEST initiative maintaining the ecological and evolutionary (http://ec.europa.eu/environment/nature/biodiversity/be processes that sustain them (Carvalho et al. 2010; st/index_en.htm), which mobilizes local stakeholders Margules & Pressey 2000). In the last decade, to identify priority areas for action and channels with the aim of promoting the persistence of funding from different sources to research and biodiversity and other natural values (Pressey et conservation projects. However, little effort has al. 2007), reserve selection has advanced to been devoted specifically to island ecological spatial conservation prioritization (Kukkala & networks, and in particular, to pollinating insects. Moilanen 2013). This has been carried out with Insects are responsible for 78 to 94% of the application of statistical modeling techniques pollination across all flowering plants and 75% of and numerical methods and also with the global food crops worldwide (Klein et al. 2007; assistance of decision-making theory to inform Ollerton et al. 2011; Winfree et al. 2011). the rational allocation of resources that are Therefore, maintaining the diversity of pollinators available for conservation planning (Moilanen et is of critical importance to preserve gene flow and al. 2009). Biodiversity concerns have also to be community stability in plant communities incorporated into the policies and practices of (Steffan-Dewenter & Westphal 2008; Cranmer et sectors such as agriculture, tourism and transport al. 2012). Oceanic islands usually feature less that operate outside protected areas, rendering complex networks with lower numbers of essential the development of conservation pollinator species, a high number of generalist planning products that are accessible and useful species and less redundancy in comparison with for local decision-makers in land-use planning continental settings (Olesen et al. 2002; Whittaker (Pierce et al. 2005; Primack 2006). Unprotected & Fernández-Palacios 2007). Hence, pollinator land or alternative land uses make different networks on oceanic islands have been considered contributions to the conservation of biodiversity, highly vulnerable to any kind of disturbance and have different implementation and (Traveset 2002), making them a priority target for management costs (Wilson et al. 2010). future conservation planning on islands (Kaiser- Among the most threatened ecosystems on Bunbury et al. 2017; Kaiser-Bunbury & Blüthgen Earth, oceanic islands are probably the places 2015). where the damage induced by the current global The Azorean archipelago, which was mostly changes is most apparent (Whittaker & covered by several types of semi-tropical Fernández-Palacios 2007). Since human evergreen forest (e.g. Laurisilva; Juniperus colonization, most oceanic islands have mountain woodlands) prior to human settlement, undergone a dramatic human mediated habitat has suffered a massive land-use change since 86 Area priorization for insect pollinator communities on an Oceanic Island human settlement 600 years ago, resulting in the design that promotes insect pollinator destruction of native habitats and introduction of preservation and monitoring plans. many exotic species (Borges et al. 2000, 2005a, 2013; Silva et al. 2008; Triantis et al. 2010; STUDY AREA Gaspar et al. 2011). As a consequence, the region The Azores archipelago is located in the Central has already experienced a high number of species North Atlantic Ocean (37 - 40º N latitude, 25 – extinctions (Borges et al. 2000; Martín et al. 31º W longitude), between Southern Europe 2008; Alcover et al. 2015; Terzopoulou et al. (Portugal) and the east coast of North America. 2015) while recent estimations suggest that more The Azores is a relatively recent archipelago than half of the extant forest arthropod species comprising nine islands and several additional might eventually be driven to extinction in the islets (França et al. 2005). At the time of human near future (Triantis et al. 2010). However, colonization, in the 15th century, the archipelago previous studies have shown that some Azorean was almost totally covered by native forest native and endemic arthropod species can persist consisting of Laurisilva forest i.e. a humid and adapt in non-natural areas surrounding evergreen broadleaf laurel forest and other types natural forest (Borges et al. 2000; Cardoso et al. of forest (e.g. mountain Juniperus woodlands) 2008; Gaspar et al. 2011; Fattorini et al. 2012; (see Elias el al. 2016). In 600 year human Vergílio et al. 2016). Furthermore, Picanço et al. activities have led to the destruction of 95% of (2017) have demonstrated that Azorean endemic the original native forest (Gaspar et al. 2008) and and native non-endemic insect pollinator species presently, only seven out of the